Linear displacement and strain measuring apparatus includes a linearly movable element (36), an emitter (38) disposed on the movable element to move as the element is moved, for developing predetermined patterns of electric fields which vary linearly on the emitter (38) in the direction of movement of the element, and a detector (8) disposed in close proximity to the emitter (38) adjacent the path in which moves to detect variations in the electric field patterns as the emitter (38) is moved, for producing output signals representing variation in the electric field patterns and thus the linear displacement of the movable element relative to the detector (8). By attaching the movable element (36) and the detector (8) to spaced apart locations on a specimen, strain in the specimen can be measured.